1. Field of the Invention
The present invention relates to a device for receiving an information signal indicative of a current, displacement or pressure measured by a meter or sensor and outputting the above measurement value and to a current monitoring device comprising the above device.
2. Description of the Prior Art
In the prior art, a measurement value output device for measuring a current running through a conductor, the displacement of an object to be measured or the inside pressure of a container measures a current, displacement or pressure by means of a sensor such as a current sensor, differential transformer or pressure sensor, applies the measured analog signal to a dedicated device to convert it into a digital signal indicative of the measurement value such as a current, displacement or pressure and outputs the digital signal to the outside.
For example, in a current value output device 60 for use in a device for monitoring the motor of a production line as shown in FIG. 14, an AC current “i” running through the power line 2 of a motor 1 is measured by current measurement means 61, this measured current signal is amplified by a detection circuit 62 to detect the above current value, the signal is applied to an A/D converter 63 to convert it into a digital signal, and the current value converted into the digital signal by the A/D converter 63 is output to current monitoring means 80 through a microcomputer 70 to monitor a time change in the measured current value.
However, since the size (measurement value) of the detected current is output as a digital value in the current value output device 60 of the prior art, a dedicated device such as the above A/D converter 63 is required and at least eight connection lines for connecting the dedicated device to the microcomputer 70, which depends on the accuracy of the measurement value, are necessary, thereby taking time and labor for wiring.
In an application field where real-time measurement is not necessary, such as the monitoring of the motor current of a production line, as shown in FIG. 15, the monitoring of a current value at predetermined time intervals suffices and the above device for outputting the measurement value (current value) all the time is not efficient.
It is an object of the present invention which has been made in view of the above problems of the prior art to provide a measurement value output device which is used to monitor a measurement value at predetermined time intervals, a measurement value monitoring device for monitoring the above output value, a current value output device for outputting a current value running through a power line at predetermined time intervals, and a current monitoring device for monitoring the above current value.